Bending wave or distributed mode loudspeakers (DML) are described in International application WO97/09842, U.S. Pat. No. 6,332,029 and other documents in the name New Transducers Ltd. Such loudspeakers may be used in applications where the loudspeaker element has additional functionality. For example, International applications WO97/09843, WO97/09853 and WO01/31971 describes the use of such panels as a ceiling tile, in a projection screen and in a keyboard, respectively.
Furthermore, applications of DML technology have extended to the use of both opaque and transparent loudspeaker panels incorporating touch-sensitive capability. For example, International application WO00/54548 describes electronic apparatus incorporating a loudspeaker having a bending wave panel member with a user-accessible surface, an electro-acoustic vibration exciter on the panel member to introduce bending wave energy into the panel member in response to an electrical signal applied thereto, and at least one touch-sensitive area on or associated with the user-accessible surface and responsive to user contact. International application WO01/48684 describes a contact-sensitive device comprising a transparent touch-sensitive plate mounted in front of a display device.